php include what am i doing wrong

[recklessop]

ok so i read http://www.vbulletin.com/docs/html/t..._externalfiles

and i followed it and this is my plugin

ob_start();
include('banners/showbanner.php');
$justinbanner = ob_get_contents();
ob_end_clean();


however im getting errors such as

Fatal error: Call to a member function query_read_slave() on a non-object in /home/beta/public_html/index.php on line 394

any ideas?

thanks